1. Field of the Invention
The present invention relates to the terminal structure of a storage battery for use in a sealed lead-acid battery for a motor bicycle, etc.
2. Description of Related Art
The terminal structures of storage batteries in the prior art have been known from, for example, the official gazettes of Japanese Patents Laid-Open No. 320718/1995 and No. 213302/1997. Disclosed in the former is an invention concerning the terminal structure of a lead acid battery wherein, in a notch which is formed at a corner of a cover substantially in the shape of a rectangular parallelepiped, a led-out plate portion in which one end of which is drawn out of an electrode pole is bent into an L-shape downwards, a horizontal plate portion and a vertical plate portion of the L-shaped led-out plate portion are respectively spliced to a top face and a front side face of a terminal supporter which protrudes from a bottom face of the notch, the L-shaped led-out plate portion is provided with bolt insertion holes at its positions corresponding to nut insertion grooves which are respectively formed in the top face and the front side face, a lower end of the vertical plate portion is inserted into a recessed portion which is provided in the bottom face of the notch, an L-shaped cut is provided by the side of the bolt insertion hole of the vertical plate portion, and the corresponding side edge of the vertical plate portion is bent inwards to form a stopper which stops the engagement with an upper edge of the nut insertion groove formed in the front side face, whereby the lower end of a plate terminal is prevented from coming out of the recessed portion, and the plate terminal is prevented from moving upwards and from deforming when it is bolted up.
Disclosed in the latter is an invention concerning the terminal structure of a lead acid battery wherein, in a notch which is formed at a corner of a cover substantially in the shape of a rectangular parallelepiped, a led-out plate portion in which one end of which is drawn out of an electrode pole is bent into a U-shape downwards on one end side thereof, so as to define a concave space on the resulting U-shaped portion and is bent into a U-shape upwards on an outer end side thereof, so as to define a backside space of the resulting U-shaped crooked plate portion as a nut accommodation space. Bolt insertion holes are respectively provided in a horizontal plate portion and a vertical plate portion of the U-shaped crooked plate portion, a horizontal lower plate portion which is formed by bending a lower plate portion of the vertical plate portion at a right angle inwards is snugly fit into a groove which is provided in a terminal supporter protruded from a bottom face of the notch, and a stopper portion is provided on at least one side of the groove, whereby the plate terminal is prevented from being easily deformed by a torque which is applied during bolting of the plate terminal.
In the former invention, the L-shaped cut is provided by the side of the bolt insertion hole formed in the vertical plate portion of the plate terminal, and the corresponding side edge of the vertical plate portion is bent to form the stopper which stops in engagement with the upper edge of the nut insertion groove. Therefore, the part of the vertical plate portion corresponding to the position of the bolt insertion hole becomes narrow and increases resistance to a current flowing through the plate portion. This incurs the drawback of a decrease in current which is derived to external lead wire connected to the bolt insertion hole by tightening a bolt and a nut. On the other hand, the stopper engages only the upper edge of the nut insertion groove and cannot reliably prevent the plate terminal from moving upwards and downwards.
Besides, in order to insert the lower end of the vertical plate portion of the plate terminal into the recessed portion of the notch and simultaneously to bring the stopper into engagement with the upper edge of the nut insertion groove provided on the cover side, the positional relationship between the stopper and the nut insertion groove of the cover side needs to be always constant. In mass production, however, the positional relationship is not always constant, and the stopper and the nut insertion groove sometimes involve a positional deviation therebetween. In some cases, accordingly, the stopper does not properly engage the upper edge of the nut insertion groove, so that the plate terminal cannot be assembled to the cover causing a manufactural loss.
In the latter invention, merely the horizontal lower plate portion of the vertical plate portion of the plate terminal is snugly fit into the groove of the terminal supporter. Therefore, the horizontal lower plate portion of the vertical plate portion might come out of the groove due to a very large torque which is applied when a bolt is inserted through the bolt insertion hole and is tightened.
The present invention eliminates the drawbacks of the prior art, and provides the terminal structure of a storage battery which is stably and rigidly mounted on a cover with ease and at high reliability. The present invention is easy of manufacture and involves no manufactural loss, which reliably prevents a plate terminal from twisting or deforming similarly on account of a torque produced in a bolting operation, and which can increase an externally derivable current. Concretely, a terminal structure of a storage battery wherein a plate terminal whose one end plate portion is connected to an electrode pole of the storage battery, and whose led-out plate portion led out from the electrode pole to a notch formed in a cover of the storage battery is formed into an L-shaped led-out plate portion vertically bent downwards and is provided with a bolt insertion hole, is mounted on a cover face. This terminal structure is characterized in that a lower plate portion of the vertical plate portion of the plate terminal is provided with at least one engagement portion, and that the lower plate portion of the plate terminal is pressed into a snug fit hole provided in the cover face, so as to fix the engagement portion in engagement with an opposing face of the snug fit hole. Herein, the engagement portion is formed of at least one member selected from the group consisting of convex parts, concave parts and a through hole in a desired shape.
In this manner, according to the present invention, the terminal structure is so constructed that the lower plate portion of the plate terminal is provided with an engagement portion, and that the lower plate portion is pressed into the snug fit hole provided in the face of the cover, so as to fix the engagement portion in engagement with the snug fit hole. Therefore, the plate terminal is reliably prevented from turning laterally, deforming or coming off upwards, due to the torque produced in the bolting operation, and the stable and stout terminal structure is obtained, merely by pressedly inserting the lower plate portion into the recessed snug fit hole which is provided in the bottom face of the notch formed at the corner of the cover of a storage battery body. Accordingly, the assembling operation of the terminal structure is easier and quicker than in the case of prior-art where a terminal structure is assembled by fixing the stopper of a plate terminal in engagement with a nut insertion groove, and where a storage battery including the terminal structure is manufactured. Also, the storage battery including the terminal structure of the present invention is obtained without any manufactural loss at an efficiency higher than in the prior-art case. Another advantage of the terminal structure of the present invention is that the terminal plate can derive a larger current to an external terminal than the prior-art plate terminal.